Preparation Of Nanosilver By Dopamine Method And Its Application In Antibacterial Field

Nanosilver has good antibacterial properties,and it can be combined with paper to make paper has antibacterial function so as to make paper play a new role in the field of antibacterial.Conventional methods combining them are to mix nanosilver in paint and then coat them on the surface of paper.In this paper,by situ formation method,nanosilver is produced directly on the surface of paper and the surface of fiber.It have the advantages of simple operation,good antibacterial effect and good prospects for development.In this study,PDA-nanosilver was successfully prepared by liquid-phase reduction.Different PDA-nanosilver liquid phase systems were prepared by changing the ratio of dopamine and AgNO₃.The influence of the variation of the amount of dopamine and silver nitrate on particle size and stability of nanosilver system was analyzed.On the basis of dopamine excess,the amount of silver nitrate was gradually increased,which could reduce the overall particle size of the prepared silver nanoparticles.When the concentration of dopamine is 600 mg/L,the concentration of AgNO₃ is 1400 mg/L,and the volume ratio of dopamine and AgNO₃ is 1:3,the PDA-nanosilver system with a particle size of 2-4 nm can be obtained.On the basis of volume ratio of 1:1,increasing the amount of dopamine or AgNO₃can increase the absolute value of Zeta potential of nanosilver system.The Zeta potential and stability of PDA-nanosilver system can be increased significantly by increasing the amount of AgNO₃.In-situ reaction was used to polymerize the dopamine on the paper surface and load the nanosilver layer on surface of paper so that the material had a silver white appearance which is different from the ordinary wrapping paper.Under the conditions of 600 mg/L dopamine concentration,1400 mg/L AgNO₃ concentration and each impregnated 2 h,the antibacterial rate of nanosilver functionalized antibacterial paper can reach 100%and tensile strength is 4.5kN/m,which meets the strength requirement of packaging paper.With the increase of AgNO₃concentration,the tensile strength and elongation of nanosilver functional paper decreased gradually,but bursting strength is almost invariable.Bamboo pulp was used as raw material,and the nanosilver was formed on the surface of the fiber.Combined with the screening process,the antibacterial paper with special appearance and higher recognition was obtained by mixing the nanosilver functional fibers and ordinary bamboo fibers.After 6 hours of immersion at 600 mg/L of dopamine and 1400mg/L of AgNO₃,the bacteriostatic rate of paper was 88%.After impregnating 12 h at the same concentration,the bacteriostatic rate of the paper reached 100%.Under condition of mass ratio of nanosilver fiber is 1/3 and 1/5 respectively,the length of nanoscale silver fiber has different effects on physical properties of the paper.